The cable television and telecommunications industries frequently utilize fiber optics as a transmission medium. Cable television (CATV) headends and central offices of a telecommunication company (Telcos) include numerous pieces of multi-function, fiber-dependent equipment. Fiber optic cables require special handling. Due to their brittle nature, excessive bending or twisting can damage the fibers, severely impair their functioning or break them altogether. Allowing fiber optic cables to become tangled or handling them like metal wire cables can also leave them susceptible to breakage or signal loss. Appropriate handling of the fiber optic cables within the cable headend or Telco improves service to customers and reduces expensive repairs or replacements.
By convention, cable companies and Telcos organize equipment modules by providing racks for holding the modules. The modules frequently fit within a box or chassis mounted onto the racks. Chassis often house optical electrical equipment such as transmitters, receivers, intelligent control interface modules (ICIM) and power supplies. A chassis configuration affords cable and Telco personnel easy access to the fiber optic cables (fiber) connected to various modules. Normally, modules slide into slots in the chassis. Fiber may route to and through the chassis. For example, a transmitter module design provides for inserting the module into a chassis having fiber optic connections along a front side of the chassis. Slots in the chassis hold additional equipment or devices, for example, a personal computer (PC) connection, fan trays, connectors for external devices and alarm indicators.
Equipment configured in modules and mounted in racks generate heat. A headend or central office might contain tens of racks of chassis utilized in providing services to customers. An individual rack can contain numerous chassis stacked one on top of another within the rack and, in the Telco market, the stacks may be arranged so chassis are back to back as well. Each chassis within the rack generates heat requiring dissipation. Telcos and cable providers rely on normal convection for cooling chassis in a rack. Optionally, a fan at the top of each chassis seeks to furnish supplemental cooling. But the stacked chassis result in a "chimney effect." The hot air exhaust is pulled by fans in higher chassis up the rack. This effect causes higher chassis to heat, rather than effecting the cooling the fans originally were intended to provide. Therefore, a more effective and efficient thermal management system for the chassis would contribute to the successful operation of the fibers and other equipment contained within the chassis.
Each chassis market has specific configuration requirements. The cable market chassis, referred to as the Multiple System Operator (MSO) chassis, requires fiber cable to route from the back of the chassis. The Telco market requirements differ between the U.S. and European markets (European Telecommunications Standard Industry, ETSI). Both the U.S. Telco and ETSI markets require the fiber cable to route from the front of the chassis. Furthermore, due to stacking configurations, the U.S. Telco chassis must comply with the size requirement that it be no more than twelve inches deep, while the ETSI chassis must not exceed 280 mm. In contrast, the MSO chassis mounts vertically in a rack, meaning it cannot extend more than thirty inches deep. Chassis utilized in an MSO environment allow connections from the rear of the chassis.
Presently, to serve these differing chassis markets requires a different chassis for each market. This increases the costs of manufacturing, installation and maintenance. Therefore, a need exists for a chassis adaptable to the cable and Telco markets and provides thermal management in each configuration. The differences in approach among the Telco/CATV markets substantially complicate creation of a chassis that fulfills these objectives.
This invention provides for a reconfigurable chassis for holding electrical equipment. The chassis can be reconfigured to conform to telephone company industry standards or to cable television industry standards. The reconfigurable chassis provides for thermal management of external electrical modules that are inserted into the chassis and removed from the chassis, and the chassis includes a housing into which modules are inserted. The housing includes a front portion and a back portion and also has multiple guides for holding the modules.
The chassis further includes a removable fan tray located on top of the housing. The fan tray holds fans for cooling the modules held within the housing. The fans can be situated in a first position or in a second position. When the fans are located in the first position, air is directed from the front portion of the chassis. When the fans are located in the second position, air is directed from the back portion of the chassis.
A removable rear connector panel is also provided for use with the chassis. The rear connector panel is used when electrical cables coupled to the modules are to be accessed from the back portion of the housing. In this case, the removable rear connector panel is mounted to the back portion of the housing for electrically coupling to the electrical cables that are coupled to the modules.
A removable panel bracket is used with the chassis when the electrical cables coupled to the modules are to be accessed from the front portion of the housing, in which case the removable panel bracket is mounted beneath the housing for routing the electrical cables from the back portion of the housing to the front portion of the housing.
Along with the removable panel bracket, a removable front connector panel is used when the electrical cables coupled to the modules are to be accessed from the front portion of the housing. The removable front connector panel is mounted to the front portion of the housing for electrically coupling to the electrical cables that have been routed through the removable panel bracket.